Bearing plate for supercharger

Abstract

A supercharger constructed in accordance to one example of the present disclosure includes a housing, first and second rotors, a bearing plate and a pair of sleeves. The first and second rotors are received in cylindrical overlapping chambers of the housing, the first rotor supported by a first rotor shaft, the second rotor supported by a second rotor shaft. The bearing plate is coupled to the housing and has an oil cavity side and an air cavity side. The bearing plate is formed of aluminum. The pair of sleeves can be received by the bearing plate and support respective bearings rotatably supporting respective first and second axle shafts. The pair of sleeves are formed of steel.

What is claimed is: 
     
         1 . A supercharger comprising:
 a housing;   a first rotor and a second rotor received in cylindrical overlapping chambers of the housing, the first rotor supported by a first rotor shaft, the second rotor supported by a second rotor shaft; and   a bearing plate coupled to the housing and having an oil cavity side and an air cavity side, the bearing plate formed of aluminum; and   a pair of sleeves received by the bearing plate and that support respective bearings rotatably supporting the respective first and second axle shafts, wherein the pair of sleeves are formed of steel.   
     
     
         2 . The supercharger of  claim 1  wherein the bearings are press-fit into the sleeves. 
     
     
         3 . The supercharger of  claim 2  wherein outer races of the bearings are formed of steel whereby thermal expansion and contraction properties are similar to the sleeves such that the press-fit is maintained throughout thermal expansion and contraction events. 
     
     
         4 . The supercharger of  claim 3  wherein the sleeves each have a raised lip formed around an inner diameter thereof, wherein the raised lips provide an axial barrier from the respective bearings. 
     
     
         5 . The supercharger of  claim 1  wherein the bearing plate further comprises a pair of seal pockets, each seal pocket configured to receive a seal. 
     
     
         6 . The supercharger of  claim 5  wherein the sleeves are cast into the bearing plate during a casting process. 
     
     
         7 . The supercharger of  claim 6  wherein the bearing plate further defines radial grooves disposed outboard of the seal pockets subsequent to the casting process, the radial grooves configured to receive the respective sleeves. 
     
     
         8 . The supercharger of  claim 6  wherein the sleeves each define apertures that can receive aluminum during the casting process. 
     
     
         9 . The supercharger of  claim 1  wherein the air cavity side defines an inset portion that leads to an outlet port of the supercharger, the inset portion having pressure relief slots formed thereon corresponding to each rotor and configured to minimize pressure and heat to improve isentropic efficiency of the supercharger. 
     
     
         10 . The supercharger of  claim 9  wherein the pressure relief slots each include a pair of arcuate wall sections that converge into each other at a valley and are configured to receive a radial component of air movement at the inset portion. 
     
     
         11 . The supercharger of  claim 10  wherein the pressure relief slots each further include a forward convex wall portion configured to receive an axial component of air movement at the inset portion. 
     
     
         12 . A supercharger comprising:
 a housing having an inlet port and an outlet port;   a first rotor and a second rotor received in cylindrical overlapping chambers of the housing, the first rotor supported by a first rotor shaft, the second rotor supported by a second rotor shaft; and   a bearing plate coupled to the housing and having an oil cavity side and an air cavity side, wherein the air cavity side defines an inset portion that leads to the outlet port of the supercharger, the inset portion having pressure relief slots formed thereon corresponding to each of the first and second rotors and configured to minimize pressure and heat to improve isentropic efficiency of the supercharger.   
     
     
         13 . The supercharger of  claim 12  wherein the pressure relief slots each include a pair of arcuate wall sections that converge into each other at a valley and are configured to receive a radial component of air movement at the inset portion. 
     
     
         14 . The supercharger of  claim 13  wherein the pressure relief slots each further include a forward convex wall portion configured to receive an axial component of air movement at the inset portion. 
     
     
         15 . The supercharger of  claim 12 , further comprising:
 a pair of sleeves received by the bearing plate and that support respective bearings, the bearings rotatably supporting the respective first and second axle shafts.   
     
     
         16 . The supercharger of  claim 15  wherein the bearing plate is formed of aluminum and the pair of sleeves are formed of steel. 
     
     
         17 . The supercharger of  claim 16  wherein the bearings are press-fit into the sleeves. 
     
     
         18 . The supercharger of  claim 17  wherein outer races of the bearings are formed of steel whereby thermal expansion and contraction properties are similar to the sleeves such that the press-fit is maintained throughout thermal expansion and contraction events. 
     
     
         19 . The supercharger of  claim 18  wherein the sleeves each have a raised lip formed around an inner diameter thereof, wherein the raised lips provide an axial barrier from the respective bearings. 
     
     
         20 . The supercharger of  claim 19  wherein the bearing plate further defines radial grooves disposed outboard of the seal pockets, the radial grooves configured to receive the respective sleeves, wherein the sleeves are cast into the bearing plate during a casting process.